i have a dual in single out cat so would it be easier to cut it off and figure out a way to weld it back up or just gut it out ..... how would you gut out the cat?... thanks

 

Why would you cut it off then weld it back up?

 

no i mean cut the cat off and weld up pipes in its place...but the only reason i dont like that idea is cuz its a DI/SO...

 

can someone explain the process of gutting out the cat... step by step...if any websites are known to show this please let me know...thanks

 

Put it in a vice and shove a pipe or pry bar inside and break it all out.

Illegal and kills exhaust flow unless you can fit a y pipe inside. No real productive reason to do it.

 

I disagree with ken, i did this to my truck and i noticed a diffrence in truck power and responsiveness. My cat was might plugged up though.

I cut my cat out with a sawzall.

Took a piece of big rebar and stuck it into the cat, hammered it down, pulled out moved repeated about 5-6 times, then started ramming rebar, down into cat and loosing comb. Picked up cat and hit the side of it with a rubber mallet and comb would come out the bottom repeated this cycle for about 45min to an hour before i was done.

I did notice power and tone diffrence in my truck but my cat was real plugged from mud and water and such. (long story)

 

The only other way would be to cut a 3 sided square (2 1/2" X 2 1/2") towards the back bottom of the converter. Lift the flap up and knock everything out of it with a long punch or chisel, if there's a screen in there, get that out too. Then knock the flap back down, turn your welder down low and weld the flap closed. It's very hard to weld so you should be a pretty good welder if you want to attempt this method. It's a hard, dusty, nasty job and the truck will have a hollow sound. If your cat is not clogged, you'd be doing a lot of work with little if any benefit.

 

But that doesnt fix the problem of the open chamber that the exhaust now has to go through, expand, cool, and then try to get back through to go through the rest of the system.

A gutted cat is bad for flow. Again, there is no logical reason to do it when there are inexpensive high flow cats, or just leave the damn thing alone. They flow better than most poeple realise.

I could think of plenty of other areas that the effort / gains ratio would be much better.

 

i would like to here some of these kens, I do know that a newer factory cat will flow good. But older cats do plug up over time. Where else do you get bettflow in a factory system.

 

Headers. Much better reward for the effort.
Most Y pipes suck. A better flowing one will sometimes give better gains than headers.
Whats the point of gutting a cat if you still have the restrictive muffler and pipe? Upgrade those and get better gains.

If your talking cheap mods, I would rather spend my time opening up the intake side, getting rid of resonators and restrictions that are on some intake tubing, add some timing, or just tune the engine up. Even someone with little mechanical knowledge can cut a stock muffler off and clamp a better flowing one in its place. All can give better gains than a gutted cat.

My .02 is that it is only half the job. At the very least weld a pipe inside the cat so flow isnt disturbed. In your case if it was that plugged up I can understand why you gutted it. I just dont understand the people on here that constantly want to remove or gut a perfectly good piece when it really isnt needed.

 

If your old cat is in good condition, ther eis no reason to replace or gut it. Doing so is illegal. If you are looking for maximum performance, you really need to approach the exahust system as a whole. It will only flow as well as its weakest point, and in factory systems, those weak points are the factory y-pipes and the factory muffler.

A gutted cat will only perform better if it was previously plugged. Don't confuse an increase in sound levels with performance. If it was my vehicle, I would replace it with a high flow cat, and even then, only if something was wrong with the original or I was doing some other modification that would require the cat replacement.

 

Good info kens, I do agree to aproaching an exhaust system as a whole. Do you think you get better power with mufflers and cats as apposed to a straight piped exhasust system? Not talkin legalities here, just performance gains or losses. From a high flow cat and a good quality muffler and the same exhaust system just with straight pipes. Performance loss, or performance gains? I do also agree with the opening up of the intake side also, i know my stock intake was very restrictive it had a 1"x4" slot for the intake, bye bye stock, hello K&N. Suggestions on timing advancement?

 

just buy a performance cat, the vehicle is designed for optimum performance with it. so just get a better one. a good cat flows just as well as no cat...

 

There are power gains with a properly designed straight pipe, however, the difference on a stock motor is ignorable, you would not be able to feel the difference. You would need either a dyno or a racetrack to determine the difference. There is not enough of a difference to justify the pollution and the potential health risks of carbon monoxide poisoning.

There are a few converter systems out there that are restrictive. Any GM with a bead type converter is highly restrictive. That is why Ford doesn't use them. Also the large converters, that we in the industry refer to as a torpedo, found on Ford trucks with either the 5.8L heavy duty models, and all 7.5L under 10,000 lbs, plus many of the 6.8L and the heavy duty 5.4L are highly restrictive by virtue of their size. These converters have such a large cross section that they act as an expansion chamber, plus there are three bricks inside what offer resistance to the air passing through. Since the gases have to slow down so much because of the cross section, the friction of the catalyst can be significant. In cases such as bead types and torpedos, there are high flow converters that are smaller and less restrictive.

 

If you want to gut the cats, put a piece of straight pipe all the way through the inside of the cat. Doing so will eliminate any turbulance caused by the hollowed out converter body.